Variable-resistance device.



E. WBINTRAUB.

VARIABLE RESISTANCE DEVICE.

APPLICATION FILED AUGJS, 1911.

1 21 1 0,848, Patented Sept. 15, 1914.`

' may call boro-carbon,

UNITED STTES" nzncnxnr. warmen-UB, l

nnitc'rmc comenzar,

VARIABLE-RESISTANCE DEVICE.

1,110,848. Speeih d! mfffent- Patented Sept. 15,1914..

Application led August 18, 1911. Serial No. 644,803.

To all whom t may concern.'

Be it-known that I, Ezncnmr. WmNrRAUB, a citizen of the United States, residing at ynn, county Vof Essex, State 0f Massachusetts, have invented certain new and useful provements in vices, of which the following is al specication.

My invention relates to variable resistance contacts, such as microphones,` variable pressure regulators, or the ike.

It is well known that when an electric circuit contains an imperfect carbon contact produce variations in its electrical resistance. This propertyof carbon is utilized, for example, in telephone transmitters.

In accordance with my invention, amaterial containing elemental boron and a material capable of combining or alloying therewith to modify its resistance, as for example, carbon, almnimum,magnesium, and like, is employed in place of carbon in a microphone, or similar variable contact resistance device. Preferably, I use a material containing boron and carbon. 0

In the accompanying drawings, Figure 1 showsdiagrammatically a variable resistance contact made with a vibrating diaphragm, and Fig. 2 is a sectional view of a te ephone transmitter in which the boron material may be used.

The material employed in accordance with my invention may be made by a number of methods, as disclosed in my Patent No. 1,019,393. For example, to produce a material containing boron and carbon, which I a carbon filament may e presence of a mixture of Elemental be heated in th boric chlorid bon, or other conductive material, both the Variable-Resistance De-` Aprotective atmosphere.

through a Wi boron and carbon being in a finely divided state. The mixture is then pressed up into coherent form either with or without a small amount of carbonaceous binder, is baked and then is fused in a high potential arc in a Various other methods are disclosed in Patent No.. 1,019,393.

construcit is employed diagrammati and a boronwith current cally in Fig. l a diaphragm 1 containing contact 2, provided connections. I have sh phone transmitter containing granular boron he art. is transmitter is of the usual construction, having a back or frame 4, a mouthpiece 5, a diaphragm 6 and suitable means for making current connecwell understood those skilled in the art of telephony.

s a resistance-varying element, borocarbon possesses the advantage of having a higher resistance than the Various forms of carbon, and its resistance may be varied 'e range by varying the content of carbon, aluminium, etc., as the case may be. The igher specific resistance enables higher voltages to be used in the circuit taining the microphone or other variable resistance device. T e boron alloys in their physical characteristics are superior also in purposes. hat I claim as new, Letters Patent of the current connections therefor, and means for exerting a variable pressure upon said material. Y

2. In a microphone, a resistance-varying element containing boron in the elemental Q state, and a conductive element associated making said material part of an electric therewith. circuit.

3. In a microphone, a conductive contact material consisting of boron combined with 5 carbon.

4. In a microphone, a diaphragm, a resistance-varying material consisting of carbon and boron, and current connections In Witness whereof, I haye hereunto set my hand this sixteenth day of August, -1911 EZECHIEL WEINTRAUB.

Witnesses:

JOHN A. MoMANUs, Jr., RoBERT SHAND.

f. 1 l Copies of this patentmay be obtained for ve cents each, by addressing the commissioner of Yatents,

Washington, D. G. 

